Mutant AD6, defective in cell-substratum adhesion, has a defect in N-acetylglucosomine acetylase and a decrease in binding of Epidermal Growth Factor. An antibody of GPP78, a protein that accumulates in AD6 and glucose-starved cells, shows that GRP 78 is located in internal membranes, and therefore is unlikely to participate in glucose transport as previously suggested.